Defect Passivation Using a Phosphonic Acid Surface Modifier for Efficient RP Perovskite Blue-Light-Emitting Diodes
Jayanta Kumar Mishra1,2, Natalia Yantara1, Anil Kanwat1
1Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore.
ACS Applied Materials & Interfaces
|May 23, 2022
Summary
Octyl phosphonic acid (OPA) effectively passivates lead (Pb2+) defects in blue perovskite light-emitting diodes (PeLEDs). This defect passivation enhances crystallization and boosts device performance, increasing photoluminescence quantum yield (PLQY) and external quantum efficiency (EQE).
Area of Science:
- Materials Science
- Optoelectronics
- Solid-State Chemistry
Background:
- Perovskite-based optoelectronic devices, particularly blue light-emitting diodes (PeLEDs), require effective defect management for improved performance.
- The emission properties of blue PeLEDs are critically dependent on the n-domain distribution in Ruddlesden-Popper perovskite films.
- Additives play a dual role as crystallization modifiers and defect passivators, necessitating detailed studies on their impact.
Purpose of the Study:
- To investigate the role of octyl phosphonic acid (OPA) as an additive in blue emissive PeLEDs.
- To demonstrate OPA's capability in passivating uncoordinated Pb2+ defects, which are known sources of nonradiative recombination.
- To analyze the effect of OPA on the crystallization and n-domain formation in perovskite films.
Main Methods:
- Utilized spectroscopic techniques including X-ray photon-spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) to confirm OPA's binding with Pb2+.
- Employed photoluminescence quantum yield (PLQY) measurements to quantify defect passivation effectiveness.
- Conducted steady-state and transient absorption (TA) measurements to study modifications in film crystallization and n-domain formation.
Main Results:
- OPA successfully binds to and passivates unpaired Pb2+ defect sites in perovskite films.
- OPA treatment modifies crystallization, promoting enhanced n-domain formation.
- Significant improvements were observed in PeLED performance: PLQY increased up to 53% and external quantum efficiency (EQE) reached 3.7% at 485 nm.
Conclusions:
- Octyl phosphonic acid is a highly effective additive for passivating Pb2+ defects in blue PeLEDs.
- OPA treatment enhances both the optical properties (PLQY) and device efficiency (EQE) of blue PeLEDs.
- The study highlights OPA's potential for advancing the development of high-performance blue perovskite optoelectronics.
